Mold for piston packing



P. W. DEM PS EY MOLD FOR PISTON PACKING Original Filed Oct. 28, 1953 1 1 2. i 23 /Z 37 A? 1 l 1 I I i 1 /0 3/33 /6 60 a4 P/f (2; a0 29 25 a INVENTOR PHILIP W. DEMPEEY BYv I ATTORNEY Patented Feb. 23, 1937 Nl'lED srrss The Westinghouse Air Brake Company, Wilmoi-ding, Pa, a corporation of Pennsylvania Original application October 28, 1933, Serial No.

695,638. Divided and this application February 19, 1935, Serial No. L173 3 Claims.

7 This invention relates to molds for making pis-v ton packings, and this application is a division of my copending application Serial No. 695,638, filed October 28, 1933, for a Process of making cylinder packing.

A principal object of the present invention is to provide an improved mold for carrying out the process for making piston packing as described in my aforesaid application.

More detailed objects and advantages of the present invention will be apparent from the following description, which is illustrated in connection with the attached drawing, wherein,

Figure 1 is a cross sectional view of the mold '15 showing the component parts in assembled relation.

Figure 2is a partial cross sectional view showing the top part of the mold removed.

Figure 3 is a fragmentary detail view along the line 33 of Figure 1.

Figure 4 is a view depicting a manner of opening the mold assembly.

As shown in the drawing, the mold comprises three sections, a bottom or base section Ill, an inner or plug section 12, and an upper or ring section l4. These three sections cooperate in molding under heat and pressure a suitable substance placed therein to form a circular, imperforate, flexible, piston packing as is indicated in Figures 1 and 2 at P.

The bottom or base section ID has a concave mold surface l5 surrounded by an annular ridge It. At the bottom of the concavity l5 are a plurality of arcuate grooves l? for forming arcuate bosses on the finished packing P.

The inner or plug section l2 has a convex mold surface l8 which is complementary to the concavity !5 in the base section It. This section is also provided with a frusto-conical boss I 9 which serves as a centering guide for the upper or ring section It.

The upper or ring section It is of annular configuration and is adapted to make metal to metal contact with the lower or base section it at 20 and with the inner or plug section l2 at 2|. The ring section I l is provided with an annular over hanging portion 22 adapted to bear upon an annular, upwardly projecting, flange 23 integral with the lower or base section It. The annular flange 23 also serves to assist in centering the upper or ring section M at contacting surfaces 24. A recess 25 in the upper section is formed complementary to the annular ridge It, as shown in the drawing. When the three mold sections 55 ID, l2 and M are assembled as shown in Figure 1, a space is defined between the three sections having the exact contour of the finished packing P.

Because of the presence of the annular ridge it for forming the corrugation of the packing P,

gases generated in the central portion ofthe packing P during the molding operation do not readily flow toward the peripheral edge of the packing. It is therefore necessary to provide means through which the gases may be vented from the central portion of the packing. The base section It is therefore provided with a central bore 28 in which is inserted a plug 2t tight enough to be retained therein but having suiiicient clearance between itself and the bore to permit gases to escape to the atmosphere thereby. The plug as is provided with an annular groove for receiving any excess material flowing through this clearance space.

The upper or ring section i l is provided with annular grooves 3i and 32, which cooperate respectively with annular groove 33 in the base section I5 and annular groove Ell in the inner section 82. These grooves function to carry away the excess material due to overflow and function in the manner disclosed in my Patent 1,910,525, issued May 23, 1933. Gases generated within the mold-during operation may also escape to the atmosphere through these grooves.

The inner or plug section 92 is provided with a recess or bore 36, which is threaded for receiving a screw plug 37 having a key hole slot 38 therein for receiving a key lug 39 with wings 4i] thereon adapted to engage arcuate cams M provided with inclined cam surfaces. The key lug 3% is secured to or formed integral with a handle 42 and when the key lug is inserted in the slot 38 and the handle 42 turned approximately d5 degrees, the wings 49 engage and irictionally lock with the inclined surfaces of the cams ll.

The handle 42 is provided with extensions t3 overlying the upper or ring section it, so that when the key lug 39 is locked in the key hole slot 38, as just described, the inner or plug section i2 is drawn into close engagement with the upper section I I. This permits the plug and upper sections to be handled as a unit when it is desired to separate these two mold sections from the lower or base section It. The operating handle 42 may be readily detached from the two mold sections I2 and l t by turning the handle so that the lug wings register with the key hole slot 38, at which time the handle may be withdrawn without disturbing the two mold sections.

In carrying out a molding operation with the afo-redescribed mold, the operating handle 42 is attached to the plug section l2 and upper section [4, as just described, and these two sections removed from contact with the base section Ill. The uncured packing blank is inserted in the lower section It and the two removed sections then reassembled with the lower section. The assembled mold sections with the enclosed uncured blank are then placed in an hydraulic press, suitable pressure applied to press the mold sections firmly together, and then subjected to the desired temperature, as is more fully described in my copending process application Serial No. 695,- 638, hereinbefore mentioned.

After the curing operation has been completed, the hydraulic pressure is released and the mold is withdrawn from the press and suitably placed for opening. In order that the mold may be opened with safety to the operator, a forked tool, as shown at 45, may be employed. Such a tool may comprise a handle 46 having forked elements ll, each of which is provided with an inwardly extending lug 68 adapted to interfit the annular slot formed between the overhanging portion of the upper section it and a similar overhanging portion 49 of the lower section it, as is clearly depicted in Figure 1. By suitably manipulating the forked tool 45 the upper mold sections may be pried loose from the lower mold section, and then the upper sections removed by gripping the handle 5-2. The finished packing P will adhere to the upper mold sections because of an annular bead 58 on the packing.

After the upper two mold sections have been removed from the lower mold section, the handle it? may be turned to the position where it is removable from the two upper mold sections, and these two sections may then be separated. The corrugated portion of the packing will then project above the inner or plug section l2, and the packing may thus be readily removed from the inner section by gripping this corrugation.

While I have described one detailed form that my improved mold may take, it will be obvious to those skilled in the art that a number of modifications and changes therein may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

l. A mold for molding a piston packing having a peripheral corrugation, comprising in combination, a base section having a concave surface circumscribed by an annular ridge, an inner section having a convex surface complementary to said concave surface and coacting therewith for forming a body portion of the packing, an upper section having an annular recess complementary to said annular ridge on said base section and coacting therewith for forming the peripheral corrugation of said packing, and being adapted to overlie said inner section when said three sections are assembled together, said three sections being separably removable, and means associated with said inner section for causing the packing to adhere to this section when said base and upper sections are removed from the packing following a molding operation, whereby the peripheral corrugation of the packing is exposed and may be gripped to remove the packing from the inner section.

2. A mold for molding a piston packing having a peripheral corrugation, comprising in combination, a base section having a concave surface circumscribed by an annular ridge, an inner section having a convex surface complementary to said concave surface and coacting therewith for forming a body portion of the packing, an upper section having an annular recess complementary to said annular ridge on said base section and coacting therewith for forming the peripheral corrugation or" said packing, and being adapted to overlie said inner section when said three sections are assembled together, said three sec tions being separably removable, means associated with said inner section for causing the packing to adhere to this section when said base and upper sections are removed from the packing following a molding operation, whereby the peripheral corrugation of the packing is exposed and may be gripped to remove the packing from the inner section, and detachable means for looking said inner and upper sections together during a molding operation.

3. A mold for molding a piston packinghaving a peripheral corrugation, comprising in combination, a base section having a concave surface circumscribed by an annular ridge, an inner section having a convex surface complementary to said concave surface for forming a body portion of the packing, an upper section having an annular recess complementary to said annular ridge on said base section for forming the peripheral corrugation of the packing, and being adapted to overlie said inner section when said three sections are assembled together, said three sections being separably removable, said inner section having a recess for causing the packing to adhere to this section when said base and upper sections are removed from the packing following a molding operation, whereby the peripheral corrugation of the packing is exposed and may be gripped to remove the packing from the inner section, and a handle device having a key for engaging a slot in the inner section for locking the inner and upper sections together during a molding operation, and being adapted to be rotated to disengage said key from said slot to unlock said two sections.

PHILIP W. DEMPSEY. 

